Fuel heater



April 9; 1'940 l M. E. CHANDLER 2,196,330

FUEL HEATER,

Original Filed April 7, 1932 ranma Apr. 9, 194e UNITED STATES FUEL HEATER Milton E. Chandler, Birmingham, Mich., assignor to' Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April '1, 1932, serial No. 603,877 v y Renewed December 24, 1937 5 claims. (ci. 12s-12a) This invention relates to manifold heaters, and more particu1ar`y to a device for utilizing the heat 'of the exhaust gases of an internal combustion engine to heat the fuel mixture passing 5 to the engine.

Heating of the fuel mixture passing to an internal combustion engine is advantageous when the engine is cold in order to promote'the volatilization of the fuel and thus facilitate cold starting, but is disadvantageous after the engine has been warmed up, since the addition of heat beyondthat necessary to smooth running decreases the volumetric eiciency of the engine.

' It is also desirable that the rate of heat transfer 15 between the exhaust gases and the fuel mixture be varied as a function of engine speed, since even a cold engine will operate satisfactorily at high speeds under light loa'd` without heat being added to the fuel mixture, but will require more -0 heat as the load increasesand the engine speed decreases. l

It is an object of the present invention to provide an improved intake manifold heater wherein the factors of temperature and engine speed are coordinated to control the rate of heat exchange between the exhaust and intake manifolds.

vA further object of the invention is to provide c 40 exhaust manifold which is of special construc" tion and which leads to an exhaustpipe I4. Located between the exhaust manifold I2 and pipe I4, and preferably formed integral with the exhaust manifold, is a section It, of substantially rectangular cross section and constituting a casing for an unbalanced gate valve Il which is ilxedto a shaft 2l rotatably journalled in the casing.

Above the casing. It and communicating therevv'with is a hollow member 22, preferably a casting.

th'e'invention is of -course applicable to other types of A gasket 2t of heat-inand constituting a heater or stove for the fuel mixture suppliedvby a carburetor 25, illustrated Vj :as ofthe downdraft, double-barrel type, although carburetor and stove as shown. Fines 24 receive the fuel mixture from the carburetorv and are preferably formed of thin sheets of copper or other material of high heat conductivity. Their lower ends arei seated in parallel bores 5 formed in a member 21 which may be formed integral with member 22 andwhich has horizontal passages 2B leading to the intake manifold (not shown). The lower ends of lthe bores are closed by means of plates or domes 29 seated 10 therein and preferably formed of thin copper plates to facilitate the heat exchange. Flues 24 and member 21 are spaced from the inner walls of member 22 to permit the exhaust gases to circulate on all sides thereof. Flanges 30 and 3l are for'med in casing I6 in such relation to valve I8 that when valve I8 is held in the position indicated in full lines in the drawing the exhaust gases will be deected by the valve and will pass upwardly around iiues 24 and 20 downwardly to the left of ange 20 and valve I8 tol the exhaust pipe I4. The valve and other parts are preferably streamlinedl to oier a smooth passageway to the exhaust gases.

A' lever 33 is fixed to shaft 20 in such relation 25 valve is in'its fullline position, and carries at its outer end aweight 34, so that it tends to move valve I8 in the clockwise direction. A bimetallic element in the form of a spiral spring has its 30 inner` end xed to shaft 20 and its outer end formed with a` flange 3B designed to abut against an adjustable stop screw 28 which is threaded in a lug formed integral with the outer wall of the casing I8.

Element 2B is so constructed that it tends to coil more closely upon itself when heated and has an initial tension such that at ordinaryv atmospheric temperatures it urges valve I8 in the counterclockwise direction against the flange 40 "with sumcient force to overcome the clockwise force of lever 23 and also the force of the exhaust gases, provided that the pressure of the exhaust gases against valve Il is low. In this position of valve Il. the fuel mixture receives the full heating eifectof the exhaust gases. As the engine warms up, however, the temperature of element v2l rises and the force exerted by' it decreases, leavingl valve Il'free to oscillate under the innuence of varying exhaust veloci- ,ties',.so,that the heating effect o n the fuel mixture is a function of engine speeds. At this stage, if the engine speed is low. the valve 4I8 l may assume the intermediate position indicated Aat Ila,perniittingaptiono fthoexhaustgases to pass in heat-exchanging relation to domes 29 and then pass between the valve and ange 30 to the exhaust pipe. When the engine is fully warmed up element 35 has coiled upon itself to such an extent that it exerts no force on the shaft 20, leaving the position of valve I8 to be governed solely by the weight 34 and the pressure of the exhaust gases, whereupon it moves to the position indicated at |8b, in which position the exhaust gases pass directly to the exhaust pipe I@ without heating the fuel mixture.

Although the invention has been described with particular reference to a speciiic embodiment thereof, it may be embodied in other forms and is not intended to be limited except by the terms of the following claims.

I claim:

1. A fuel mixture heater for an internal combustion engine, comprising a path for exhaust gases in heat exchange relation to the fuel mixture passing to the engine, an exhaust pipe by-passing said path, a pressure-responsive valve controlling the flow through said path and said pipe, gravity means urging the Valve toward one extreme position, and temperature-responsive means operative at low temperatures to urgey the valve toward its opposite position.

2. In a device of the class described, means forming an exhaust passage, a valve in said passage, yielding means normally tending to open said valve, and a bi-metallic thermostat for closing said valve, said thermostat closing said valve against the force of said yielding means when the temperature is low, and having one end entirely free to move without interference by said valve or said yielding means whenever a predetermined temperature is exceeded.

3. In a device of the class described, means forming an exhaust passage, an eccentrically mounted valve for controlling passage of gas `through said passage, passages for conveying gas away from said passage at a point anterior to said valve and returning it to said passage at a point posterior to said valve, yielding means tending to hold said valve in open position, and a bi-metallic thermostat for closing said valve when the temperature is low, said thermostat being supported at one end only, and the other end of said thermostat being in operative relation to said valve mechanism only when the temperature is comparatively low,

4. In a device of the class described, means forming an exhaust passage, a buttery valve mounted in said passage, a shaft for said valve, a bi-metallic thermostat carried by said shaft for operating it in one direction, and yielding means forcperating said shaft in the other dlrection, said thermostat being located between said yielding means and the exhaust passage.

5. A fuel mixture heater for an internal combustion engine, comprising an exhaust passage,

a heating chamber designed to'receive exhaust gases from the exhaust passage, a fuel mixture conduit extending into heat exchange relation to the heating chamber. a pressure responsive valve operative in one position to deflect the exhaust gases from the exhaust passage into the heating chamber and operative in another, non-deecting, position to form a partition between the exhaust passage and the heating chamber to exclude the gases therefrom, said valve being unbalanced in such manner as to be urged at all times by the pressure of the exhaust gases toward the non-deccting position. yielding means urging the valve toward the non-deecting position, and temperatureresponsive means operative at low temperatures to urge the valve toward the deilecting position and inoperative at all times tofurge the valve toward the nondeiiectlng position.

MILTON E. CHANDLER. n 

